JPS6412012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an audio signal recording method and a reproduction method thereof, and particularly relates to an original audio signal consisting of an analog signal,
It relates to an audio signal recording method in which at least one of the digital audio signals obtained by converting this original audio signal into a digital code is modulated, frequency-division multiplexed, and recorded on a recording medium, and when playing back, the recording is performed as described above. The present invention relates to an audio signal reproducing method characterized in selectively reproducing one of an audio signal based on an analog signal and an audio signal based on a digital signal from a recording medium.

A conventional recording and reproducing system for digitized audio signals is explained using a block diagram as shown in FIG. 1, which is an enlarged version of CEShannon's communication channel model. In the figure, 1 is an information source, 2 is an information source encoder,
3 is a transmission line encoder, 4 is a transmission line, 41 is a noise, 5
is a transmission path decoder, and 6 is an information source decoder. Note that the subscripts s and r are added to distinguish the same components on the recording side and the reproduction side, respectively.

In the digital recording/playback system configured in this way, the information source 1 is an analog audio signal, which is sampled, quantized, and encoded by the information source encoder 2, and converted into a digital code.
Further, the signal is converted by a transmission line encoder 3 into a transmission line code 7 matching the characteristics of the transmission line 4 and sent to the transmission line 7. The transmission line encoder 3 is generally an error correction encoder 3.
1, a synchronization adder 32, and a modulator 33. In addition, the transmission path 4 includes writing to, reading from, and in some cases duplicating the medium, and the effects of distortion, dust, and scratches that occur in each of these three processes are all handled by the transmission path. This is interpreted as external noise 41 relative to the noise. On the other hand, the signal 7r read out from the transmission line 4 is decoded by the transmission line decoder 5, and further restored to the original analog signal 1r by the information source decoder 6 and output. The transmission line decoder 5 is composed of an error correction decoder 51, a synchronization identification separator 52, a demodulator 53, etc. in correspondence with the transmission line encoder 3, and the information source decoder 6 includes a D/A converter and a D/A converter. Contains an interpolator.

By the way, in general, in a recording/playback system, there are cases in which a medium recorded by a certain device is played back by that device, and cases in which the medium is played back by another device. In particular, when disks are used as media, the latter example is overwhelming, and the ability to obtain a large number of copies is even a major feature. The conditions for such a system to become widespread are not only that the quality of the reproduced audio signal is good, but also that it can be reproduced using the same reproduction medium with an extremely simple and low-end reproduction device. However, the transmission path decoder 5 and information source decoder 6 in digital recording and playback systems
Components such as these require extremely high precision and are therefore expensive, and even if LSI technology is promoted in the future, it will be difficult to create an extremely low-performance playback device.
Therefore, as it stands now, two types of media coexist: conventional analog recording media for low-priced products, and digital recording media for high-quality products, which poses a huge problem in terms of reproduction productivity. big.

This invention was made in view of the above-mentioned drawbacks of the conventional system, and provides an audio signal recording device that performs FM modulation on a digitized audio signal and an analog audio signal before digitization, frequency division multiplexes the signal, and optically records the same on a disk medium. The purpose of this proposal is to provide uniformity to the duplication disk medium, improve duplication productivity, and promote the spread of the system.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a configuration example of an acoustic signal reproducing device according to the present invention, FIG. 3 is a spectrum diagram of a signal that is frequency division multiplexed and sent to a transmission path according to the present invention, and FIG. 4 is a reproduction according to the present invention. It is a diagram showing an example of the simplest configuration of the device. In the figure, 8 is a first bandpass filter (hereinafter abbreviated as "BPF");
is an FM modulator that modulates an analog acoustic signal with FM,
10 is a second BPF, 11 is an adder, and 12 is an amplitude limiter, which functions to remove the amplitude modulation division that the frequency division multiplexed signal from the adder 11 receives during multiplexing. 13 is a signal sent to the transmission line 4. Further, (FDFM) and (FAFM) are respective center frequencies when FM modulating the digitized audio signal and analog audio signal, and 14 is an FM demodulator.

Next, the operation will be explained. The original analog audio signal is converted into a transmission line code 71 in the same manner as in the conventional apparatus (FIG. 1), but the number is different because there are limitations on the modulation method in the case of the present invention. The transmission line code 71, that is, the signal obtained by FM modulating the digitized acoustic signal at the center frequency FDFM, has its band limited by the first BPF 8 and is applied to the adder 11. On the other hand, the original analog audio signal 1 is applied to the FM modulator 9 as it is analog, and the center frequency
It is FM modulated by FAFM and the modulation output is 91s.
Bandwidth is limited by BPF10 and adder 11
added to. The output of the adder 11 is sent to the amplitude limiter 1.
When limiting by 2, a new transmission line code 13 is obtained in which the amplitude fluctuation component generated by adding the digitized audio signal and the analog audio signal is suppressed, and this spectrum becomes, for example, as shown in FIG. This waveform 13 is sent to the transmission line 4, and in the case of reproduction, the simplest and least expensive configuration is as shown in FIG. 4. Transmission line 4
The second BPF10 of the waveform 13r that came out from
A component 91r centered on FAFM is extracted, and the original analog audio signal 1r is reproduced simply by demodulating this with the FM demodulator 14. or,
If you want to obtain high-quality reproduced sound, extract the component 71r centered on FDFM from the waveform 13r coming out of the transmission line 4 using the first BPF 8.
This can be restored using a transmission path decoder and an information wave decoder.

In the above explanation, FAFM is treated as one type, but as shown in Figure 5, there are multiple analog FMs.
It is also possible to provide transmission channels, and multiple audio channels can be transmitted separately.

As described above, according to the present invention, the amplitude is limited after frequency division multiplexing, and then optically recorded on a disk medium, so that noise-free, high-quality acoustic signals can be selected and reproduced. I can do it. Furthermore, frequency division multiplexing improves the utilization efficiency of the recording surface of the disk medium, and requires only one expensive recording/reproducing head, thereby preventing high costs. Furthermore, the same reproduction medium can be reproduced with high precision by both the highest quality reproduction device and the simplest and lowest-performance reproduction device, which has a significant effect on improving reproduction productivity and promoting the spread of the system.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional digital recording and playback system, Fig. 2 is a block diagram showing an embodiment of a recording device according to the present invention, and Fig. 3 is a spectrum diagram of a transmission line signal in the embodiment of Fig. 2. , FIG. 4 is a configuration diagram showing the simplest example of a reproducing apparatus when the present invention is adopted, and FIG. 5 is a spectrum diagram of a transmission line signal in another embodiment of the present invention. In each figure, 1 is an original analog acoustic signal, 2 is an information source encoder, 3 is a transmission line encoder, 4 is a transmission line, 5 is a transmission line decoder, 6
is an information source decoder, 7 is a conventional transmission line code, 8 is a first BPF, 9 is an analog FM modulator, and 10 is a second
BPF, 11 is an adder, 12 is an amplitude limiter, 1
3 is a transmission line signal, 14 is an FM demodulator, 71 is a digitized audio signal modulation output, and 91 is an analog audio signal modulation output. In each figure, the same numbers indicate the same or equivalent components. Note that the subscripts s and r
are added to distinguish the same components on the recording side and the reproduction side, respectively.

Claims (1)

[Claims] 1. An information source encoder that inputs an acoustic signal consisting of an analog signal and converts this analog signal into a digital signal, modulates the digital signal from this information source encoder at a first center frequency, and generates a code suitable for the disk medium. a first bandpass filter that limits the band of the digital signal from the transmission line encoder, inputs an acoustic signal consisting of the analog signal, and modulates the analog signal at a second center frequency. a second bandpass filter that has a different bandwidth than the first bandpass filter and limits the band of the analog signal from the frequency modulator;
an adder that adds the digital signal from the bandpass filter and the analog signal from the second bandpass filter; an amplitude limiter that limits the amplitude of the output signal from the adder; An acoustic signal recording device that optically records an acoustic signal consisting of an analog signal and a digital signal.